Photo-polymerizable, negative-type photosensitive resin compositions are used for color filter photoresists, overcoat photoresists, column spacers, photo-shielding insulating materials and the like. Such a composition generally comprises an alkaline soluble resin, a polymer having at least one ethylenically unsaturated bond, a polymerizable initiator and a solvent.
Such a photosensitive resin composition is used in such a manner that the composition is coated on a substrate to form a thin film, a predetermined portion of the thin film is exposed to irradiation using a photo-mask and the non-exposed region is developed, to form a pattern.
Applications of liquid crystal displays (LCDs) have been expanded from conventional notebook monitors to desktop monitors, LCD TVs and the like, thus inevitably causing an increase in concentration of pigment present in a color filter photoresist and fine-dispersion of the pigment in order to realize high-quality colors. In order to realize thinner films, a concentration of light-shielding material, such as carbon black or titanium black, in a resin black matrix composition gradually increases.
As the concentration of the pigment or light-shielding material in the photosensitive resin composition increases, a level of irradiation transferred to the bottom of patterned films is rapidly decreased. Conventional compositions cannot satisfy requirements such as heat-resistance and chemical-resistance of LCD panel makers who decrease the level of irradiation exposed in order to improve production efficiency. In an attempt to satisfy these requirements, the amount of the binder increases to improve heat-resistance and chemical-resistance and photosensitivity is improved using a high-sensitivity photo-polymerization initiator. However, there is a limitation in increasing the concentration of a binder in view of the content of the composition. Also, this increase causes an increase in viscosity of the composition and makes highly sensitive photo-polymerization initiator expensive.
Accordingly, there is a need for approaches to multifunctional monomers in order to improve chemical-resistance, heat-resistance and development margin.